Spark plug cap for an internal combustion engine



FIG. 1 is a front perspective view of a spark plug cap for an internal combustion engine showing our new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is a right side view thereof, the left side view being symmetrical to the right side view.

The broken line portion of the figure drawings is included to show unclaimed subject matter only and forms no part of the claimed design. 

The ornamental design for a spark plug cap for an internal combustion engine, as shown and described. 